Infrared and ultraviolet radiation. Properties of ultraviolet radiation and its effect on the human body

It is difficult to overestimate the influence of the sun's light on a person - under its action, the most important physiological and biochemical processes are launched in the body. The solar spectrum is divided into infrared and visible parts, as well as the most biologically active ultraviolet part, which has a great impact on all living organisms on our planet. Ultraviolet radiation is the short-wave part of the solar spectrum that is imperceptible to the human eye, which has an electromagnetic character and photochemical activity.

Due to its properties, ultraviolet is successfully used in various fields. human life. UV radiation has received wide use in medicine, since it is able to change the chemical structure of cells and tissues, having a different effect on humans.

UV wavelength range

The main source of UV radiation is the sun. The share of ultraviolet in the total flux sunlight fickle. It depends on:

• time of day;
• time of year;
• solar activity;
• geographic latitude;
• the state of the atmosphere.

Despite the fact that the celestial body is far from us and its activity is not always the same, a sufficient amount of ultraviolet reaches the Earth's surface. But this is only its small long-wavelength part. Short waves are absorbed by the atmosphere at a distance of about 50 km from the surface of our planet.

The ultraviolet range of the spectrum, which reaches the earth's surface, is conditionally divided by wavelength into:

• far (400 - 315 nm) - UV - A rays;
• medium (315 - 280 nm) - UV - B rays;
• near (280 - 100 nm) - UV - C rays.

The effect of each UV range on the human body is different: the shorter the wavelength, the deeper it penetrates through the skin. This law determines the positive or Negative influence ultraviolet radiation on the human body.

Near-range UV radiation most adversely affects health and carries the risk of serious illnesses.

UV-C rays should be scattered in the ozone layer, but due to poor ecology, they reach the surface of the earth. Ultraviolet rays of range A and B are less dangerous, with strict dosing, radiation of the far and medium range has a beneficial effect on the human body.

Artificial sources of ultraviolet radiation

The most significant sources of UV waves affecting the human body are:

• bactericidal lamps - sources of UV - C waves, used to disinfect water, air or other objects external environment;
• arc of industrial welding - sources of all waves of the solar spectrum;
• erythema fluorescent lamps- sources of UV-waves of the range A and B, used for therapeutic purposes and in solariums;
• industrial lamps are powerful sources of ultraviolet waves used in production processes for fixing paints, inks or curing polymers.

The characteristics of any UV lamp are the power of its radiation, the range of the wave spectrum, the type of glass, the service life. From these parameters depends on how the lamp will be useful or harmful to humans.

Before irradiation with ultraviolet waves from artificial sources for the treatment or prevention of diseases, one should consult with a specialist to select the necessary and sufficient erythemal dose, which is individual for each person, taking into account his skin type, age, existing diseases.

It should be understood that ultraviolet is electromagnetic radiation, which has not only positive influence on the human body.

A bactericidal ultraviolet lamp used for tanning will bring significant harm, not benefit to the body. Only a professional who is well versed in all the nuances of such devices should use artificial sources of UV radiation.

The positive effect of UV radiation on the human body

Ultraviolet radiation is widely used in the field of modern medicine. And this is not surprising, because UV rays produce analgesic, soothing, anti-rachitic and anti-spastic effects. Under their influence occurs:

• the formation of vitamin D, necessary for the absorption of calcium, the development and strengthening of bone tissue;
• decreased excitability of nerve endings;
• increased metabolism, because it causes the activation of enzymes;
• vasodilation and improved blood circulation;
• stimulating the production of endorphins - "happiness hormones";
• increase in the speed of regenerative processes.

The beneficial effect of ultraviolet waves on the human body is also expressed in a change in its immunobiological reactivity - the body's ability to show protective functions against pathogens of various diseases. Strictly dosed ultraviolet irradiation stimulates the production of antibodies, thereby increasing the resistance of the human body to infections.

Exposure to UV rays on the skin causes a reaction - erythema (redness). There is an expansion of blood vessels, expressed by hyperemia and swelling. The decay products formed in the skin (histamine and vitamin D) enter the bloodstream, which causes general changes in the body when exposed to UV radiation.

The degree of development of erythema depends on:

• UV dose values;
• range ultraviolet rays;
• individual sensitivity.

With excessive UV radiation, the affected area of ​​the skin is very painful and swollen, a burn occurs with the appearance of a blister and further convergence of the epithelium.

But skin burns are far from the most serious consequences prolonged exposure to ultraviolet radiation. The unreasonable use of UV rays causes pathological changes in the body.

The negative impact of UV radiation on humans

Despite its important role in medicine, The health risks of UV radiation outweigh the benefits.. Most people are not able to accurately control the therapeutic dose of ultraviolet radiation and resort to protective methods in a timely manner, therefore, its overdose often occurs, which causes the following phenomena:

• headaches appear;
• body temperature rises;
• fatigue, apathy;
• memory impairment;
• cardiopalmus;
• loss of appetite and nausea.

Excessive tanning damages the skin, eyes, and immune (defense) system. Perceived and visible effects of excessive UV exposure (burns of the skin and mucous membranes of the eyes, dermatitis and allergic reactions) disappear within a few days. Ultraviolet radiation accumulates over a long period of time and causes very serious diseases.

The effect of ultraviolet radiation on the skin

A beautiful even tan is the dream of every person, especially the fairer sex. But it should be understood that skin cells darken under the influence of the coloring pigment released in them - melanin in order to protect against further exposure to ultraviolet radiation. That's why tanning is a protective reaction of our skin to damage to its cells by ultraviolet rays. But it does not protect the skin from the more serious effects of UV radiation:

1. Photosensitivity - increased susceptibility to ultraviolet light. Even a small dose of it causes severe burning, itching and sunburn of the skin. Often this is associated with the use of medications or the use of cosmetics or certain foods.
2. Photoaging. UV-A rays penetrate into the deeper layers of the skin, damaging the structure connective tissue, which leads to the destruction of collagen, loss of elasticity, to early wrinkles.
3. Melanoma - skin cancer. The disease develops after frequent and prolonged exposure to the sun. Under the influence of an excessive dose of ultraviolet radiation, the appearance of malignant formations on the skin or the degeneration of old moles into a cancerous tumor.
4. Basal cell and squamous carcinoma is a non-melanoma skin cancer that is not fatal, but requires surgical removal of affected areas. It is noticed that the disease occurs much more often in people who work for a long time under open sun.

Any dermatitis or skin sensitization phenomena under the influence of ultraviolet radiation are provoking factors for the development of skin cancer.

The effect of UV waves on the eyes

Ultraviolet rays, depending on the depth of penetration, can also adversely affect the condition of the human eye:

1. Photophthalmia and electrophthalmia. It is expressed in redness and swelling of the mucous membrane of the eyes, lacrimation, photophobia. Occurs when safety rules are not observed when working with welding equipment or in people who are in bright sunlight in a snow-covered area (snow blindness).
2. Growth of the conjunctiva of the eye (pterygium).
3. Cataract (clouding of the lens of the eye) is a disease that occurs to varying degrees in the vast majority of people in old age. Its development is associated with exposure to ultraviolet radiation on the eye, which accumulates over a lifetime.

Excess UV rays can lead to various forms of eye and eyelid cancer.

The effect of ultraviolet radiation on the immune system

If the dosed use of UV radiation helps to increase the body's defenses, then excessive exposure to ultraviolet radiation depresses immune system . This has been proven in scientific research US scientists on the herpes virus. Ultraviolet radiation changes the activity of cells responsible for immunity in the body, they cannot restrain the reproduction of viruses or bacteria, cancer cells.

Basic precautions for safety and protection against exposure to ultraviolet radiation

To avoid negative consequences effects of UV rays on the skin, eyes and health, every person needs protection from ultraviolet radiation. When forced to stay in the sun for a long time or at a workplace exposed to high doses of ultraviolet rays, it is imperative to find out if the UV index is normal. In enterprises, a device called a radiometer is used for this.

When calculating the index for meteorological stations takes into account:

• wavelength of the ultraviolet range;
• concentration of the ozone layer;
• solar activity and other indicators.

The UV index is an indicator of the potential risk to the human body as a result of exposure to a dose of ultraviolet radiation. The index value is evaluated on a scale from 1 to 11+. The norm of the UV index is considered to be no more than 2 units.

High index values ​​(6-11+) increase the risk of adverse effects on human eyes and skin, so protective measures must be taken.

1. Use Sunglasses(special masks for welders).
2. In the open sun, you should definitely wear a hat (with a very high index - a wide-brimmed hat).
3. Wear clothes that cover your arms and legs.
4. On uncovered areas of the body wear sunscreen with an SPF of at least 30.
5. Avoid being outdoors, not protected from sunlight, space from noon to 4 pm.

Performance simple rules safety will reduce the harmfulness of UV radiation to humans and avoid the occurrence of diseases associated with the adverse effects of ultraviolet radiation on his body.

Who should not be exposed to ultraviolet light?

The following categories of people should be careful with exposure to ultraviolet radiation:

• with very light and sensitive skin and albinos;
• children and teenagers;
• those who have many birthmarks or nevi;
• suffering from systemic or gynecological diseases;
• those who had skin cancer among close relatives;
• taking some long-term medications(doctor's consultation required).

UV radiation is contraindicated for such people even in small doses, the degree of protection from sunlight should be maximum.

The influence of ultraviolet radiation on the human body and its health cannot be unequivocally called positive or negative. There are too many factors to consider when it affects a person in different conditions environment and radiation from various sources. The main thing to remember is the rule: any human exposure to ultraviolet light should be kept to a minimum before consultation with a specialist and strictly dosed according to the doctor's recommendations after examination and examination.

Light it is a collection of electromagnetic waves of various lengths. The wavelength range of visible light is from 0.4 to 0.75 microns. Areas of invisible light are adjacent to it - ultraviolet or UV radiation(from 0.4 to 0.1 µm) and infrared or IR radiation(from 0.75 to 750 µm).

Visible light brings us most of the information from the outside world. In addition to visual perception, light can be detected by its thermal effect, by its electrical action, or by the chemical reaction it causes. The perception of light by the retina of the eye is one example of its photochemical action. In visual perception, a certain wavelength of light is accompanied by specific color. So radiation with a wavelength of 0.48-0.5 microns will be blue; 0.56-0.59 - yellow; 0.62-0.75 red. Natural White light, is a set of waves of different lengths propagating simultaneously. It can be break down into components and strain them out using spectral instruments ( prisms,gratings,filters).

Like any wave, light carries energy with it, which depends on the wavelength (or frequency) of the radiation.

Ultraviolet radiation, being shorter wavelength, is characterized by higher energy and stronger interaction with matter, which explains its widespread use in practice. For example, ultraviolet radiation can initiate or enhance many chemical reactions. The influence of ultraviolet radiation on biological objects is significant, for example, its bactericidal action.

It should be remembered that ultraviolet radiation is very strongly absorbed by most substances, which does not allow the use of conventional glass optics when working with it. Up to 0.18 microns, quartz, lithium fluoride are used, up to 0.12 microns - fluorite; for even shorter wavelengths, reflective optics must be used.

Even more widely used in technology is the long-wave part of the spectrum - infrared radiation. Note here night vision devices, infrared spectroscopy, heat treatment of materials, laser technology, measurement of the temperature of objects at a distance.

thermal radiation- electromagnetic radiation emitted by a substance and arising due to its internal energy. Thermal radiation has a continuous spectrum, the position of the maximum of which depends on the temperature of the substance. With its increase, the total energy of the emitted thermal radiation increases, and the maximum moves to the region of small wavelengths.

Application: thermal imaging systems. Thermal imaging is the obtaining of a visible image of bodies by their thermal (infrared) radiation, either intrinsic or reflected; used to determine the shape and location of objects in the dark or in optically opaque media. These systems are used for diagnostics in medicine, navigation, geological exploration, flaw detection, etc. Optical radiation receivers are devices in which infrared radiation from an object is converted into visible radiation, such as photocells, photomultipliers, photoresistors, etc. .

Rice. 12.2. Photomultiplier:

1 - photo cathode; 2 - screen; 3-10 - cathodes; A - anode;

An interesting property of IR rays was recently discovered by Polish scientists: direct irradiation of steel products with the light of infrared lamps inhibits corrosion processes not only under normal storage conditions, but also with an increase in humidity and sulfur dioxide content.

There is also a method for determining the exposure of photoresistors based on diacompounds and azides during photolithography. In order to improve reproducibility and increase the yield of suitable devices, a semiconductor epitaxial material with a photoresist deposited on it is irradiated with ultraviolet or visible light, and the exposure is determined by the disappearance time of the absorption band of the photoresist film in the region of 2000-2500 cm to the minus first degree. Here they are irradiated with short-wavelength light, and the change in properties is recorded by absorption in the infrared region - 2000 cm to the minus first degree correspond to a wavelength of 3.07 μm.

Light radiation can transfer its energy to a body not only by heating it or exciting its atoms, but also in the form of mechanical pressure. light pressure It manifests itself in the fact that a distributed force acts on the illuminated surface of the body in the direction of light propagation, which is proportional to the density of light energy and depends on the optical properties of the surface. The light pressure on a fully reflective mirror surface is twice that of a fully absorbing one, other things being equal.

This phenomenon can be explained both from the wave and corpuscular points of view on the nature of light. In the first case, this is the result of the interaction of the electric current induced in the body by the electric field of the light wave with its magnetic field according to Ampère's law. In the second case, it is the result of the transfer of photon momentum to an absorbing or reflecting wall.

The light pressure is small. So, bright sunlight presses on 1 sq.m. black surface with a strength of only 0.4mg. However, the ease of controlling the light flux, the "oxeontact" effect and the "selectivity" of light pressure in relation to bodies with different absorbing and reflecting properties make it possible to successfully use this phenomenon in invention (for example, a photon rocket).

Light pressure is also used in microscopes to compensate for small changes in mass or force. The measuring photoelectric device determines what value of the light flux, and, consequently, the light pressure, was required to compensate for the change in the mass of the sample and restore the equilibrium of the system.

Application of light pressure:

A method for pumping gases or vapors from a vessel to a vessel by creating a pressure drop on a partition having a hole separating both vessels, in order to increase pumping efficiency, a light beam emitted, for example, by a laser, is focused on the hole in the partition;

The method according to claim 1, characterized in that for the purpose of selective pumping of gases or vapors and, in particular, for the purpose of separating isotopic mixtures of gases or vapors, the width of the emission spectrum is chosen less than the frequency separation of the centers of the absorption lines of neighboring components, while the frequency of the emitter set to the center of the absorption line of the pumped out component.

With the discovery of infrared radiation, the well-known German physicist Johann Wilhelm Ritter had a desire to study the opposite side of this phenomenon.

After some time, he managed to find out that at the other end it has considerable chemical activity.

This spectrum became known as ultraviolet rays. What it is and what effect it has on living terrestrial organisms, let's try to figure it out further.

Both radiations are in any case electromagnetic waves. Both infrared and ultraviolet, they limit the spectrum of light perceived by the human eye on both sides.

The main difference between these two phenomena is the wavelength. Ultraviolet has a fairly wide wavelength range - from 10 to 380 microns and is located between visible light and X-rays.

Differences between infrared and ultraviolet

IR radiation has the main property - to radiate heat, while ultraviolet has a chemical activity, which has a tangible effect on the human body.

How does ultraviolet radiation affect humans?

Due to the fact that UV is divided by the difference in wavelength, they biologically affect the human body in different ways, so scientists distinguish three sections of the ultraviolet range: UV-A, UV-B, UV-C: near, middle and far ultraviolet.

The atmosphere that envelops our planet acts as a protective shield that protects it from the Sun's ultraviolet flux. Far radiation is retained and absorbed almost completely by oxygen, water vapor, carbon dioxide. Thus, insignificant radiation enters the surface in the form of near and medium radiation.

The most dangerous is radiation with a short wavelength. If short-wave radiation falls on living tissues, it provokes an instant destructive effect. But due to the fact that our planet has an ozone shield, we are safe from the effects of such rays.

IMPORTANT! Despite natural protection, we use some inventions in everyday life that are sources of this particular range of rays. This welders And ultraviolet lamps which, unfortunately, cannot be abandoned.

Biologically, ultraviolet affects human skin as a slight reddening, sunburn, which is a fairly mild reaction. But it is worth considering individual feature skin that can react specifically to UV radiation.

Exposure to UV rays also adversely affects the eyes. Many are aware that ultraviolet affects the human body in one way or another, but not everyone knows the details, so let's try to understand this topic in more detail.

UV mutagenesis or how UV affects human skin

Completely avoid exposure to sunlight skin covering you can't, it's going to lead to very unpleasant consequences.

But it is also contraindicated to go to extremes and try to acquire an attractive shade of the body, exhausting yourself under the merciless rays of the sun. What can happen in case of uncontrolled stay under the scorching sun?

If redness of the skin is found, this is not a sign that after a while, it will pass and a nice, chocolate tan will remain. The skin is darker due to the fact that the body produces a coloring pigment, melanin, which fights against the adverse effects of UV on our body.

Moreover, redness on the skin does not remain long, but it can lose elasticity forever. Epithelial cells may also begin to grow, visually reflected in the form of freckles and age spots, which will also remain for a long time, or even forever.

Penetrating deep into tissues, ultraviolet light can lead to ultraviolet mutagenesis, which is damage to cells at the gene level. The most dangerous can be melanoma, in case of metastasis of which death can occur.

How to protect yourself from ultraviolet radiation?

Is it possible to protect the skin from the negative effects of ultraviolet radiation? Yes, if, while on the beach, you follow just a few rules:

1. It is necessary to be under the scorching sun for a short time and at strictly defined hours, when the acquired light tan acts as photoprotection of the skin.
2. Be sure to use sunscreen. Before you buy this kind of product, be sure to check if it can protect you from UV-A and UV-B.
3. It is worth including in the diet foods that contain the maximum amount of vitamins C and E, as well as rich in antioxidants.

If you are not on the beach but have to be outdoors, you should choose special clothing that can protect your skin from UV.

Electrophthalmia - the negative effect of UV radiation on the eyes

Electrophthalmia is a phenomenon that occurs as a result of the negative effects of ultraviolet radiation on the structure of the eye. UV waves from the middle ranges in this case are very damaging to human vision.

Electrophthalmia

These events most often occur when:

• A person observes the sun, its location, without protecting the eyes with special devices;
• Bright sun in open space (beach);
• The person is in a snowy area, in the mountains;
• Quartz lamps are placed in the room where the person is located.

Electrophthalmia can lead to corneal burns, the main symptoms of which are:

• Tearing of the eyes;
• Significant pain;
• Fear of bright light;
• Redness of the protein;
• Edema of the epithelium of the cornea and eyelids.

About the statistics, the deep layers of the cornea do not have time to be damaged, therefore, when the epithelium heals, vision is fully restored.

How to provide first aid for electrophthalmia?

If a person is faced with the above symptoms, it is not only aesthetically unpleasant, but can also cause unimaginable suffering.

First aid is pretty simple:

• First rinse eyes with clean water;
• Then apply moisturizing drops;
• Put on glasses;

To get rid of pain in the eyes, it is enough to make a compress from wet black tea bags, or grate raw potatoes. If these methods do not help, you should immediately seek help from a specialist.

To avoid such situations, it is enough to purchase social sunglasses. The UV-400 marking indicates that this accessory is able to protect the eyes from all UV radiation.

How is UV radiation used in medical practice?

In medicine, there is the concept of "ultraviolet starvation", which can occur in case of prolonged avoidance of sunlight. In this case, unpleasant pathologies may arise, which can be easily avoided using artificial sources of ultraviolet radiation.

Their small impact is able to compensate for the lack of winter vitamin D deficiency.

In addition, such therapy is applicable in case of joint problems, skin diseases and allergic reactions.

With UV radiation, you can:

• Increase hemoglobin, but lower sugar levels;
• Normalize the work of the thyroid gland;
• Improve and eliminate respiratory problems and endocrine system;
• With the help of installations with ultraviolet radiation, rooms and surgical instruments are disinfected;
• UV rays have bactericidal properties, which is especially useful for patients with purulent wounds.

IMPORTANT! Always, using such radiation in practice, it is worth familiarizing yourself not only with the positive, but also with the negative aspects of their impact. It is strictly forbidden to use artificial, as well as natural UV radiation as a treatment for oncology, bleeding, stage 1 and 2 hypertension, and active tuberculosis.

Infrared radiation - is a variety electromagnetic radiation, which occupies the range from 0.77 to 340 microns in the spectrum of electromagnetic waves. In this case, the range from 0.77 to 15 microns is considered short-wave, from 15 to 100 microns - medium-wave, and from 100 to 340 - long-wave.

The short-wave part of the spectrum is adjacent to visible light, and the long-wave part merges with the region of ultrashort radio waves. Therefore, infrared radiation has both the properties of visible light (it propagates in a straight line, reflects, refracts like visible light) and the properties of radio waves (it can pass through some materials that are opaque to visible radiation).

Infrared emitters with a surface temperature of 700 C to 2500 C have a wavelength of 1.55-2.55 microns and are called "light" - they are closer in wavelength to visible light, emitters with a lower surface temperature have a longer wavelength and are called "dark".

What is the source of infrared radiation?

Generally speaking, any body heated to a certain temperature radiates thermal energy in the infrared range of the spectrum of electromagnetic waves and can transfer this energy through radiant heat transfer to other bodies. Energy transfer occurs from a body with a higher temperature to a body with a lower temperature, while different bodies have different radiating and absorbing capacities, which depend on the nature of the two bodies, on the state of their surface, etc.

Application



Infrared rays are used for medical purposes if the radiation is not too strong. They have a positive effect on the human body. Infrared rays have the ability to increase local blood flow in the body, increase metabolism, and expand blood vessels.

• Remote control

Infrared diodes and photodiodes are widely used in remote controls, automation systems, security systems, etc. They do not distract a person's attention due to their invisibility.

• When painting

Infrared emitters are used in industry for drying paintwork surfaces. The infrared drying method has significant advantages over the traditional, convection method. First of all, this is, of course, an economic effect. The speed and energy expended with infrared drying is less than those with traditional methods.

• Food sterilization

With the help of infrared radiation, food products are sterilized for the purpose of disinfection.

• Anti-corrosion agent

Infra-red beams are applied, for the purpose of prevention of corrosion of the surfaces covered with a varnish.

• food industry

A feature of the use of infrared radiation in the food industry is the possibility of penetration of an electromagnetic wave into such capillary-porous products as grain, cereals, flour, etc. to a depth of up to 7 mm. This value depends on the nature of the surface, structure, properties of the material and the frequency response of the radiation. An electromagnetic wave of a certain frequency range has not only a thermal, but also a biological effect on the product, it helps to accelerate biochemical transformations in biological polymers (starch, protein, lipids). Conveyor drying conveyors can be successfully used when laying grain in granaries and in the flour-grinding industry.


Ultraviolet radiation (from ultra... and violet), ultraviolet rays, UV radiation, electromagnetic radiation invisible to the eye, occupying the spectral region between visible and X-rays within wavelengths l 400—10 nm. Whole area Ultraviolet radiation conditionally divided into near (400-200 nm) and distant, or vacuum (200-10 nm); The last name comes from the fact that Ultraviolet radiation this area is strongly absorbed by air and its study is carried out using vacuum spectral instruments.

Positive Effects

In the twentieth century, it was first shown how UV radiation has a beneficial effect on humans. The physiological effect of UV rays was studied by domestic and foreign researchers in the middle of the last century (G. Varshaver. G. Frank. N. Danzig, N. Galanin. N. Kaplun, A. Parfenov, E. Belikova. V. Dugger. J. Hassesser, H. Ronge, E. Biekford, and others) |1-3|. It has been convincingly proven in hundreds of experiments that radiation in the UV region of the spectrum (290-400 nm) increases the tone of the sympathetic-adrenaline system, activates protective mechanisms, increases the level of nonspecific immunity, and also increases the secretion of a number of hormones. Under the influence of UV radiation (UVR), histamine and similar substances are formed, which have a vasodilating effect, increase the permeability of skin vessels. Changes in carbohydrate and protein metabolism in the body. The action of optical radiation changes pulmonary ventilation - the frequency and rhythm of breathing; increases gas exchange, oxygen consumption, activates the activity of the endocrine system. Particularly significant is the role of UV radiation in the formation of vitamin D in the body, which strengthens the musculoskeletal system and has an anti-rachitis effect. Of particular note is that long-term UVR deficiency can have adverse effects on the human body, referred to as "light starvation". The most common manifestation of this disease is a violation of mineral metabolism, decreased immunity, fatigue, etc.

Action on the skin

The action of ultraviolet radiation on the skin, exceeding the natural protective ability of the skin (tanning) leads to burns.

Prolonged exposure to ultraviolet radiation contributes to the development of melanoma, various types of skin cancer, accelerates aging and the appearance of wrinkles.

With controlled exposure of the skin to ultraviolet rays, one of the main positive factors is the formation of vitamin D on the skin, provided that the natural fatty film is preserved on it. Sebum oil on the surface of the skin is exposed to ultraviolet light and then reabsorbed into the skin. But if you wash off the sebum before going out into the sunlight, vitamin D cannot be formed. If you take a bath immediately after sun exposure and wash off the fat, then vitamin D may not have time to be absorbed into the skin.

Action on the retina

Ultraviolet radiation is imperceptible to the human eye, but with intense exposure it causes a typical radiation injury (retinal burn). So, on August 1, 2008, dozens of Russians damaged the retina during solar eclipse, despite numerous warnings about the dangers of watching him without eye protection. They complained of a sharp decrease in vision and a spot before their eyes.

However, ultraviolet is extremely necessary for the human eye, as most ophthalmologists attest. Sunlight has a relaxing effect on the muscles around the eyes, stimulates the iris and nerves of the eyes, and increases blood circulation. Regularly strengthening the nerves of the retina with sunbathing, you will get rid of the painful sensations in the eyes that occur during intense sunlight.


Sources:

The energy of the Sun is electromagnetic waves, which are divided into several parts of the spectrum:

• x-rays - with the shortest wavelength (below 2 nm);
• the wavelength of ultraviolet radiation is from 2 to 400 nm;
• the visible part of the light that is captured by the eye of humans and animals (400-750 nm);
• warm oxidizing (over 750 nm).

Each part finds its use and has great importance in the life of the planet and all its biomass. We will consider what rays are in the range from 2 to 400 nm, where they are used and what role they play in people's lives.

History of the discovery of UV radiation

The first mentions date back to the 13th century in the descriptions of a philosopher from India. He wrote about the invisible violet light that he discovered. However, the technical capabilities of that time were clearly not enough to confirm this experimentally and study it in detail.

It was possible five centuries later, a physicist from Germany, Ritter. It was he who conducted experiments on silver chloride on its decay under the influence of electromagnetic radiation. The scientist saw that this process was faster not in that region of the world, which had already been discovered by that time and was called infrared, but in the opposite one. It turned out that this is a new area, still not explored.

Thus, in 1842, ultraviolet radiation was discovered, the properties and application of which subsequently underwent a thorough analysis and study by various scientists. A great contribution to this was made by such people as: Alexander Becquerel, Warsawer, Danzig, Macedonio Melloni, Frank, Parfenov, Galanin and others.

general characteristics

What is the use of which today is so widespread in various industries human activities? Firstly, it should be noted that this light appears only at very high temperatures from 1500 to 2000 0 C. It is in this interval that UV reaches its peak activity in terms of exposure.

By its physical nature, this electromagnetic wave, the length of which varies over a fairly wide range - from 10 (sometimes from 2) to 400 nm. The entire range of this radiation is conditionally divided into two areas:

1. near spectrum. It reaches the Earth through the atmosphere and the ozone layer from the Sun. Wavelength - 380-200 nm.
2. Far (vacuum). It is actively absorbed by ozone, air oxygen, atmospheric components. It is possible to study only special vacuum devices for which it got its name. Wavelength - 200-2 nm.

There is a classification of species that have ultraviolet radiation. Properties and application finds each of them.

1. Near.
2. Further.
3. Extreme.
4. Middle.
5. Vacuum.
6. Long wavelength black light (UV-A).
7. Shortwave germicidal (UV-C).
8. Medium wave UV-B.

Each species has its own wavelength of ultraviolet radiation, but they are all within the general limits already indicated earlier.

UV-A, or the so-called black light, is interesting. The fact is that this spectrum has a wavelength of 400-315 nm. This is on the border with visible light, which the human eye is able to capture. Therefore, such radiation, passing through certain objects or tissues, is capable of moving into the region of visible violet light, and people distinguish it as black, dark blue or dark purple.

The spectra produced by ultraviolet radiation sources can be of three types:

• ruled;
• continuous;
• molecular (band).

The first are characteristic of atoms, ions, gases. The second group is for recombination, bremsstrahlung radiation. Sources of the third type are most often encountered in the study of rarefied molecular gases.

Sources of ultraviolet radiation

The main sources of UV rays fall into three broad categories:

• natural or natural;
• artificial, man-made;
• laser.

The first group includes the only type of concentrator and emitter - the Sun. It is the celestial body that gives the most powerful charge of this type of waves, which are able to pass through and reach the surface of the Earth. However, not in its entirety. Scientists put forward the theory that life on Earth originated only when the ozone screen began to protect it from excessive penetration of harmful UV radiation in high concentrations.

It was during this period that protein molecules began to exist, nucleic acids and ATP. Until today, the ozone layer enters into close interaction with the bulk of UV-A, UV-B and UV-C, neutralizing them and preventing them from passing through. Therefore, protection from ultraviolet radiation of the entire planet is exclusively his merit.

What determines the concentration of ultraviolet radiation penetrating the Earth? There are several main factors:

• ozone holes;
• height above sea level;
• solstice height;
• atmospheric dispersion;
• the degree of reflection of rays from earth's natural surfaces;
• cloud vapor state.

The range of ultraviolet radiation penetrating the Earth from the Sun ranges from 200 to 400 nm.

The following sources are artificial. These include all those devices, devices, technical means that were designed by man to obtain the desired spectrum of light with given wavelength parameters. This was done in order to obtain ultraviolet radiation, the use of which can be extremely useful in various fields of activity. Artificial sources include:

1. Erythema lamps that have the ability to activate the synthesis of vitamin D in the skin. This prevents and cures rickets.
2. Devices for solariums, in which people get not only a beautiful natural tan, but are also treated for diseases that occur when there is a lack of open sunlight (the so-called winter depression).
3. Attractant lamps that allow you to fight insects indoors safely for humans.
4. Mercury-quartz devices.
5. Excilamp.
6. Luminous devices.
7. Xenon lamps.
8. gas discharge devices.
9. High temperature plasma.
10. Synchrotron radiation in accelerators.

Another type of source is lasers. Their work is based on the generation of various gases - both inert and not. Sources can be:

• nitrogen;
• argon;
• neon;
• xenon;
• organic scintillators;
• crystals.

More recently, about 4 years ago, a free electron laser was invented. The length of ultraviolet radiation in it is equal to that observed in vacuum conditions. UV laser suppliers are used in biotechnology, microbiological research, mass spectrometry and so on.

Biological effects on organisms

The effect of ultraviolet radiation on living beings is twofold. On the one hand, with its deficiency, diseases can occur. This became clear only at the beginning of the last century. Artificial irradiation with special UV-A in the required norms is capable of:

• activate the immune system;
• cause the formation of important vasodilating compounds (histamine, for example);
• strengthen the musculoskeletal system;
• improve lung function, increase the intensity of gas exchange;
• affect the speed and quality of metabolism;
• increase the tone of the body by activating the production of hormones;
• increase the permeability of the walls of blood vessels on the skin.

If UV-A enters the human body in sufficient quantities, then it does not develop diseases such as winter depression or light starvation, and the risk of developing rickets is also significantly reduced.

The effect of ultraviolet radiation on the body is of the following types:

• bactericidal;
• anti-inflammatory;
• regenerating;
• painkiller.

These properties largely explain the widespread use of UV in medical institutions any type.

However, in addition to the above advantages, there are also negative aspects. There are a number of diseases and ailments that can be acquired if you do not get enough or, on the contrary, take the considered waves in excess.

1. Skin cancer. This is the most dangerous exposure to ultraviolet radiation. Melanoma can form with excessive influence of waves from any source - both natural and man-made. This is especially true for lovers of tanning in the solarium. In everything, measure and caution are necessary.
2. Destructive effect on the retina of the eyeballs. In other words, a cataract, pterygium, or sheath burn may develop. The harmful excessive effects of UV on the eyes have been proven by scientists for a long time and confirmed by experimental data. Therefore, when working with such sources, you should observe. On the street, you can protect yourself with the help of dark glasses. However, in this case, you should be wary of fakes, because if the glasses are not equipped with UV-repellent filters, then the destructive effect will be even stronger.
3. Burns on the skin. In the summer, they can be earned if you expose yourself to UV for a long time uncontrollably. In winter, you can get them because of the peculiarity of the snow to reflect these waves almost completely. Therefore, irradiation occurs both from the side of the Sun and from the side of snow.
4. Aging. If people are exposed to UV for a long time, then they begin to show signs of skin aging very early: lethargy, wrinkles, sagging. This is due to the fact that the protective barrier functions of the integument are weakened and violated.
5. Impact with consequences over time. Contained in manifestations negative impacts not at a young age, but closer to old age.

All of these results are consequences of misdosing UV, ie. they occur when the use of ultraviolet radiation is carried out irrationally, incorrectly, and without observing safety measures.

Ultraviolet radiation: application

The main areas of use are based on the properties of the substance. This is also true for spectral wave radiation. So, the main characteristics of UV, on which its application is based, are:

• high level chemical activity;
• bactericidal effect on organisms;
• ability to induce light various substances different shades, visible to the eye human (luminescence).

This allows wide use of ultraviolet radiation. Application is possible in:

• spectrometric analyses;
• astronomical research;
• medicine;
• sterilization;
• disinfection drinking water;
• photolithography;
• analytical study of minerals;
• UV filters;
• for catching insects;
• to get rid of bacteria and viruses.

Each of these areas uses a specific type of UV with its own spectrum and wavelength. Recently, this type of radiation has been actively used in physical and chemical research (determination of the electronic configuration of atoms, the crystal structure of molecules and various compounds, work with ions, analysis of physical transformations on various space objects).

There is another feature of the effect of UV on substances. Some polymeric materials are capable of decomposing under the influence of an intense constant source of these waves. For example, such as:

• polyethylene of any pressure;
• polypropylene;
• polymethyl methacrylate or organic glass.

What is the impact? Products made from these materials lose color, crack, fade, and eventually collapse. Therefore, they are called sensitive polymers. This feature of carbon chain degradation under solar illumination conditions is actively used in nanotechnologies, X-ray lithography, transplantology, and other fields. This is done mainly to smooth out the surface roughness of the products.

Spectrometry is a major field of analytical chemistry that specializes in identifying compounds and their composition by their ability to absorb UV light of a specific wavelength. It turns out that the spectra are unique for each substance, so they can be classified according to the results of spectrometry.

Also, the use of ultraviolet germicidal radiation is carried out to attract and destroy insects. The action is based on the ability of the insect's eye to capture short-wave spectra invisible to humans. Therefore, animals fly to the source, where they are destroyed.

Use in solariums - special installations of vertical and horizontal type, in which human body exposed to UV-A. This is done to activate the production of melanin in the skin, giving it more dark color, smoothness. In addition, inflammation is dried and harmful bacteria on the surface of the integument are destroyed. Special attention should be given to the protection of eyes, sensitive areas.

medical field

The use of ultraviolet radiation in medicine is also based on its ability to destroy living organisms invisible to the eye - bacteria and viruses, and on the features that occur in the body during competent lighting with artificial or natural radiation.

The main indications for UV treatment can be summarized in several points:

1. All types of inflammatory processes, wounds open type, suppuration and open seams.
2. With injuries of tissues, bones.
3. For burns, frostbite and skin diseases.
4. With respiratory ailments, tuberculosis, bronchial asthma.
5. With the emergence and development of various types of infectious diseases.
6. For ailments accompanied by severe painful sensations, neuralgia.
7. Diseases of the throat and nasal cavity.
8. Rickets and trophic
9. Dental diseases.
10. Regulation of blood pressure, normalization of the heart.
11. The development of cancerous tumors.
12. Atherosclerosis, kidney failure and some other conditions.

All these diseases can have very serious consequences for the body. Therefore, treatment and prevention using UV is a real medical discovery that saves thousands and millions of human lives, preserving and restoring their health.

Another option for using UV with medical and biological point vision is the disinfection of premises, sterilization of work surfaces and tools. The action is based on the ability of UV to inhibit the development and replication of DNA molecules, which leads to their extinction. Bacteria, fungi, protozoa and viruses are killed.

The main problem when using such radiation for sterilization and disinfection of a room is the area of ​​illumination. After all, organisms are destroyed only with the direct impact of direct waves. Everything that remains outside continues to exist.

Analytical work with minerals

The ability to induce luminescence in substances makes it possible to use UV to analyze the qualitative composition of minerals and valuable minerals. rocks. In this regard, precious, semi-precious and ornamental stones are very interesting. What kind of shades they do not give when irradiated with cathode waves! Malakhov, the famous geologist, wrote about this very interestingly. His work tells about observations of the glow of the color palette, which minerals can give in different sources irradiation.

So, for example, topaz, which has a beautiful saturated blue color in the visible spectrum, glows bright green when irradiated, and emerald - red. Pearls cannot give any particular color at all and shimmers with many colors. The resulting spectacle is simply fantastic.

If the composition of the rock under study includes uranium impurities, then the illumination will show green color. Melite impurities give a blue, and morganite - a lilac or pale purple hue.

Use in filters

For use in filters, ultraviolet germicidal radiation is also used. The types of such structures can be different:

• hard;
• gaseous;
• liquid.

Such devices are mainly used in the chemical industry, in particular, in chromatography. With their help, it is possible to conduct a qualitative analysis of the composition of a substance and identify it by belonging to a particular class of organic compounds.

Drinking water treatment

Disinfection by ultraviolet radiation of drinking water is one of the most modern and qualitative methods its purification from biological impurities. The advantages of this method are:

• reliability;
• efficiency;
• the absence of foreign products in the water;
• security;
• profitability;
• preservation of the organoleptic properties of water.

That is why today this method of disinfection keeps pace with traditional chlorination. The action is based on the same features - the destruction of the DNA of harmful living organisms in the composition of water. Use UV with a wavelength of about 260 nm.

In addition to direct action on pests, ultraviolet light is also used to destroy residues. chemical compounds, which are used to soften, purify water: such as, for example, chlorine or chloramine.

black light lamp

Such devices are equipped with special emitters capable of producing waves of great length, close to visible. However, they still remain indistinguishable to the human eye. Such lamps are used as devices that read secret signs from UV: for example, in passports, documents, banknotes, and so on. That is, such marks can be distinguished only under the action of a certain spectrum. Thus, the principle of operation of currency detectors, devices for checking the naturalness of banknotes is built.

Restoration and determination of the authenticity of the painting

And in this area finds application UV. Each artist used white, containing different heavy metals in each epochal period of time. Thanks to irradiation, it is possible to obtain so-called underpaintings, which provide information about the authenticity of the painting, as well as about the specific technique, manner of painting of each artist.

In addition, the lacquer film on the surface of products belongs to sensitive polymers. Therefore, it is capable of aging under the influence of light. This allows you to determine the age of compositions and masterpieces of the artistic world.